Liquid, surface-active salts



United States Patent @fifice 3,054,820 Patented Sept. 18, 1862 This invention relates to liquid salts having a surfaceactive activity and their preparation and particularly to liquid surface-active amine salts of acid sulfates.

Acid sulfates corresponding to the formula C H OCH CH OSO OI-I are known in the art. They may for example be pre pared by condensing lauryl alcohol with ethylene oxide and sulfating the product thus obtained. In this process one generally starts from technically pure lauryl alcohol and uses the ethylene oxide in an amount corresponding to the desired average number of ethoxy groups. Accordingly mixtures are usually obtained in which about 25% of the compounds contain instead of the dodecyl radical another alkyl radical having from 8-16 carbon atoms, whilst the value of n may vary rather widely for the individual compounds in the mixture. These compounds upon neutralization with sodium hydroxide yield neutral salts having a very good surface-active activity. Vide in this respect Soap, Perfumery and Cosmetics, December 1956, page 1367 and Soap and Chemical Specialties, August 1956, page 45.

From both publications, it is apparent that sodium laurylsulfate, where n=0, is a solid and that with increasing values of n the consistency changes gradually through pasty to liquid. In practice, however, no compounds of the above mentioned type are used wherein n has an average value greater than 3, because the surface-active action does not increase anymore for values of n greater than 3, while at the same time with such higher values of n the cost of the product'increases. When, however, n has an average value of 3, the sodium salts are still pasty.

In practice surface-active compounds having a pasty consistency are not well adapted to be put upon the market in anhydrous state, because the pastes can only with difficulty and never completely be removed from the containers used for transport. For this reason such substances are generally put upon the market in the form of about 30% solutions. This, however, causes a strong increase in transport cost while such solutions cannot be used either for purposes requiring an anhydrous medium, if for example, the surface-active compounds are to be used as emulsifiers in anhydrous insecticidal compositions.

In the second of the above mentioned publications it is further stated that other salts of these compounds have already also been made, e.g. the triethanolamine salt. Although the above mentioned publication discloses nothing about the consistency of this salt in anhydrous condition, applicants have found by experiment, that the triethanolamine salt is also pasty in anhydrous condition for values of n ranging from 2 to 3.

It is an object of the invention to provide new salts of the acid sulfates having the above mentioned structure, said salts being liquid under normal circumstances of temperature and pressure. A further object of the invention is to provide useful methods for making such salts.

We have now found that the novel salts of compounds of the formula C H OCH CH OSO OH in which n has an average value from 2 to 3 and the dodecyl radical may be replaced partly by other alkyl radicals having from 8 to 16 carbon atoms and an amine chosen from the group of diethylamine, isopropylamine and butylethanolamine in anhydrous state are liquid under normal conditions of temperature and pressure. We have further found that such salts may be obtained by neutralizing compounds of the formula C H OCH CH OSO OH in which n has an average value of from 2 to 3 and the dodecyl radical may be partly replaced by other alkyl radicals having from 8-16 carbon atoms with an amine from the group of diethylamine, isopropylamine, butylethanolamine and mixtures thereof.

The neutralization may be carried out by adding the amine to the acid sulfates or alternatively by adding the acid sulfates to the amine. Diethylamine and isopropylamine are rather volatile substances, so that losses in these amines may occur as a result of the heat of the reaction generated at the surface. In these cases therefore we prefer to introduce the amine below the surface of the acid sulfate. It is of course advantageous to stir during the neutralization step. If desired the neutralization may be carried out with refluxing or in a closed system under a superatmospheric pressure.

Usually the neutralization is carried out preferably at temperatures somewhat above room temperature, e.g. at 30 C., because the viscosity of the mixtures is somewhat lower at such temperatures, which facilitates stirring.

The required amount of amine may easily be determined beforehand or during the neutralization by simple experiments. As the starting products are strongly acidic and the amines used are not strong bases, the amount of the latter is always greater than the equivalent amount based on the amount of the acid sulfates.

Pure mono-(dodecylpolyethoxy)-sulfates may be used as well as the corresponding products prepared from a technical grade of dodecylalcohol. For economical reasons the second procedure is preferred. It is further of course possible to isolate first the dior triethoxy compounds and to employ these compounds in the process of our invention, but as will readily be appreciated this also implies a rise of the cost.

Evidently mixtures of the above mentioned amines may also be used.

The novel products of our invention have in aqueous solution the same surface-active properties as the corresponding sodium salts, but then moreover have the advantage of being liquid in anhydrous conditions. This property makes it possible to deliver them in undiluted state to the buyer, which means an important saving in transport cost. The products of our invention dissolve Well in Water. The dissolution rate may of course be increased by heating. However, a fast dissolution takes place already at room temperature upon the addition of various compounds, such as alcohol, glycols and salts, to the products of our invention. For example, the products of our invention dissolve at sufficient rate at room temperature in a l-percent sodium chloride solution.

The fact that the products of our invention are liquid in anhydrous condition moreover renders them suitable for a number of other uses. For example they may be used as such as a shampoo in which case they are diluted by the user on the scalp with warm water. This makes it possible to market the novel products of our invention in little capsules and the like, containing the products in an amount substantially as needed for one shampooing. Contrary to the corresponding sodium salts the novel products of our invention may also be used as emulsifiers in non-aqueous systems, e.g. in non-aqueous insecticidal compositions.

As stated above a pasty product is obtained when the neutralization of the acid sulfates is carried out with triethanolamine. This is also the case when for example monoethanolamine and ethylethanolamine are used for the neutralization. Therefore it is surprising, that liquid neutralization products are obtained when using the three above mentioned amines.

The products of our invention have a great dissolving power for parafiin oil. Solutions containing up to about 25% parafiin oil are still clear.

Example I An acid sulfate was prepared by condensing a technical grade lauryl alcohol with 2.2 mols of ethylene oxide and sulfating the condensation product. 100 g. of this acid sulfate were neutralized by adding diethylamine in portions beneath the surface of the acid sulfate. During the neutralization the temperature was maintained below 30 C. by cooling. After the equivalent amount of amine has been added, the neutralization reaction was followed by taking at regular intervals samples of the reaction mixture, making a concentrated aqueous solution of these samples and exaluating the pH of these solutions. In this way so much of the amine was added that the pH of the aqueous solution was about 7. A total amount of 27.2 g. of diethyl amine was required to that effect.

In the same way 100 g. of the above mentioned acid sulfate were neutralized with 34.5 g. of isopropylamine.

The products thus obtained were clear, viscous liquids.

Example II An acid sulfate was prepared in the manner disclosed in Example I with the difference that 2.8 mols of ethylene oxide instead of 2.2 mols were used. 100 g. of this acid sulfate were neutralized with butylethanolamine while stirring, the amine being dropwise added to the surface of the acid sulfate the temperature being maintained at 30 C. After the equivalent amount of amine had been added the course of the neutralization reaction was followed in the way disclosed in Example I. It appeared that the total of 38.5 g. of butylethanolamine were required for the neutralization.

A clear, viscous liquid was obtained.

It will be understood that while there have been given herein certain specific examples of the practice of this invention, it is not intended thereby to have this invention limited to or circumscribed by the specific details of materials, proportions or conditions herein specified, in view of the fact that this invention may be modified according to individual preference or conditions without necessarily departing from the spirit of this disclosure and the scope of the appended claims.

What we claim is:

1. Liquid neutralization products of compounds of the formula C H (OCH CH OSO- OH wherein said C H radical is derived from lauryl alcohol and n is a number having an average value from 2 to 3, with an amine selected from the group consisting of diethylamine, isopropylamine, and butylethanolamine.

2. The neutralization products of claim 1, wherein the C H radical has been replaced by about 25 of alkyl radicals having from 8 to 16 carbon atoms.

3. Liquid neutralization products of compounds of the formula.

C H OCH CH OSO OH wherein said C H radical is derived from lauryl alcohol and n is a number with an average value from 2 to .3, with diethylamine.

4. The neutralization products of claim 3, wherein the C H radical has been replaced by about 25 of alkyl radicals having from 8 to 16 carbon atoms.

5. Liquid neutralization products of compounds of the formula C H (OCH CH OSO OH wherein said C H radical is derived from lauryl alcohol and n is a number having an average value from 2 to 3, with butylethanolamine.

6. The neutralization products of claim 5, wherein the C H radical has been replaced by about 25 of alkyl radicals having from 8 to 16 carbon atoms.

7. Liquid neutralization products of the formula C H (OCH CH ),,OSO OH wherein said C H radical is derived from lauryl alcohol, and has been replaced by about 25% of alkyl radicals having from 8 to 16 carbon atoms, and wherein n is a number having an average value from 2-3, with isopropylamine.

References Cited in the file of this patent UNITED STATES PATENTS 2,212,521 Harris Aug. 27, 1940 FOREIGN PATENTS 719,445 Great Britain Dec. 1, 1954 

1. LIQUID NEUTRALIZATION PRODUCTS OF COMPOUNDS OF THE FORMULA 